The generation and ready access to complex molecules with useful pharmacological properties underpins many advances in biomedical science. Development of new and efficient synthetic methodology continues to play a critical role in producing a wide array of such complex molecules. This proposal seeks support to develop new synthetic protocols based on transition metal-catalyzed reactions initiated by carbon-hydrogen bond activation reactions. While many transition metal-catalyzed processes based on oxidative addition of carbon-halogen or carbon-main group bonds to metal centers are widely applied in synthesis, relatively few processes based on carbon-hydrogen bond activation are available for construction of complex molecules. Possible advantages of such processes include readily available substrates, elimination of by-products (atom economy), potential shortening of synthetic sequences, and unique reactivity patterns. The specific aims of this proposal are to employ C-H bond activation chemistry to (1) carry out catalytic transfer dehydrogenations which will provide new methods for introducing carbon-carbon double bonds into organic molecules as well as routes to a wide variety of new synthetic building blocks and (2) achieve addition of C-H bonds of aldehydes and arenes across carbon-carbon double bonds. Each of these processes has the potential to add significantly to the ability to efficiently and rapidly synthesize complex organic molecules. [unreadable] [unreadable]